In the related art, as materials for magnetic cores of a motor, an actuator, a magnetic sensor, and the like, soft magnetic sintered materials are known which may be obtained by sintering an iron powder, an iron-based Fe—Al soft magnetic alloy powder, an iron-based Fe—Ni soft magnetic alloy powder, an iron-based Fe—Cr soft magnetic alloy powder, an iron-based Fe—Si soft magnetic alloy powder, an iron-based Fe—Si—Al soft magnetic alloy powder, an iron-based Fe—Co soft magnetic alloy powder, an iron-based Fe—Co—V soft magnetic alloy powder, and an iron-based Fe—P soft magnetic alloy powder (hereinafter, these are collectively referred to as soft magnetic particles).
On the other hand, in the case where an iron powder or an alloy powder is produced through powderization by a gas atomization method or a water atomization method, the iron powder or the alloy powder has a low specific resistance in an elementary substance state. Therefore, the following countermeasures have been taken. A surface of the iron powder or the alloy powder is coated with an insulating film or the powder is mixed with an organic compound or an insulating material; and thereby, sintering is prevented so as to increase the specific resistance. With regard to this kind of soft magnetic material, a composite soft magnetic material is suggested so as to suppress eddy current loss, and in the composite soft magnetic material, a surface of a soft magnetic particle including iron is coated with a lower layer film formed from a nonferrous metal and an insulating film including an inorganic compound.
As an example of the composite soft magnetic material, a powder magnetic core has been adapted. The powder magnetic core is obtained as follows. A composite soft magnetic material is obtained by mixing a soft magnetic powder and an insulating binder. The composite soft magnetic material is subjected to compression molding into a target shape, and the resultant compression-molded body is baked This powder magnetic core has a structure in which soft magnetic powder particles are bonded to each other through the insulating binder; and thereby, insulation between the soft magnetic powder particles is secured by the insulating binder.
In addition, with regard to an example of the powder magnetic core, there is disclosed a technology in which a silicone-based resin as a resin having an operation of reducing a magnetostriction amount is added to an Fe—Si alloy powder (the content of Si is in a range of 0.5% by mass to 3.5% by mass) to obtain a low magnetostrictive material (refer to Patent Document 1).
In addition, with regard to the kind of soft magnetic material, there is disclosed a technology of obtaining a high-strength and low magnetostrictive material. In the technology, a pure iron powder and an Fe-6.5 Si alloy powder are mixed, and kaolin, amorphous silica, an acrylic emulsion, and a lubricant are further added to the resultant mixture in such a manner that a weight ratio of an amount of the pure iron powder to the total amount becomes in a range of 10% to 55% (refer to Patent Document 2).
However, with regard to electromagnetic components for electronic apparatuses, along with miniaturization and high performance of the electronic apparatuses, relatively strict material properties are demanded, and it is necessary for the electromagnetic components not to cause a problem in a practical use. When an examination is made with respect to soft magnetic material that is used for these components, in the low magnetostrictive material that is obtained by mixing the pure iron powder and the Fe-6.5 Si alloy powder, further adding the kaolin, the amorphous silica, and the like to the resultant mixture as described above, and subjecting the resultant mixture to compression molding, and in an iron-based soft magnetic material other than an Ni—Fe alloy (Permalloy in which the content of Ni is 78.5% by weight) or an Fe—Si—Al (Sendust) alloy, a problem occurs in use in which noise is caused by magnetostriction, particularly, in a frequency range of 10 kHz or less. Therefore, there is a problem in that the soft magnetic materials are not suitable in a practical use.
Accordingly, with regard to this kind of the iron-based soft magnetic material, it is desired that a soft magnetic material is provided which has a low magnetostrictive property and a high magnetic flux density, and with the low magnetostrictive property, noise caused by magnetostriction does not occur in a practical use state.